This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Our laboratory studies the molecular and cellular biology of HSV-1 during lytic and latent infections including the mechanisms of gene silencing and reactivation. Aim 1: We investigated the roles of TR and T3 on HSV-1 gene expression and latency/reactivation. Thyroid hormone receptor (TR) responsive elements (TREs) were identified in the promoters of HSV-1 TK and LAT. We demonstrated that liganded TR repressed TK promoter activity by transfection and infection of neuronal cells. Our data also showed that the liganded TRs activated LAT transcription but repressed ICP0 transcription. Furthermore, T3-treated N2aTR[unreadable] cells were suppressive to TK expression and virus egress at low moi but the abstraction of hormone enhanced the TK expression and thus increased the release of infectious viruses. These results, for the first time, suggested that T3 could regulate the HSV-1 infections and may have a role in viral latency and reactivation. Aim 2: Additional data mining revealed novel binding elements of Early Growth Response protein -1 (Egr1) within HSV-1 ICP22 intron. Results showed that Egr1 does bind to the intron. Further studies indicated that Egr1 was rapidly induced by HSV-1 lytic infection. The transcription was initiated by viral binding to the cell membrane and the translation required the expression of viral gene products. Aim 3: In collaboration with Dr. El Sayed's laboratory, we also screened many natural compounds as potential antiviral drugs. The results showed that an alkaloid Manzamine A exhibits significant inhibitory effect on viral infection in a corneal cell line at 1 [unreadable]M. These results suggest that it may have great potential to prevent HSV-1 induced eye infection.